Soft soldering stainless steel

I've had some luck with an acid type flux.

Stainless steel flux and you need to spread the heat around. The stainless has a very low thermal conductivity so you can't just put the iron in one spot and expect to flow the entire joint.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Stainless steel flux - Back when I did a lot of this (1980s), I used Eutectic Castolin #157 for soft solder. The castolin website appears to suck rocks, so I can't confirm the number or that the stuff is still made now. Clean the metal well mechanically (brush, scotchbrite or sandpaper) first, flux quickly.

An OA torch with a long feather (absurdly carburizing flame) works nicely, as the long flame can be laid along the joint (stainless is a poor heat conductor).

with all this talk - I'd preheat in an oven to near the temp you need and then add the temp with a 150 watt iron or flame.

You are not saying if it is a tractor trailer side or ear rings. :-) There might be different issues on each size.

Mart> >

Zinc Chloride liquid flux works quite well for me. I use pure tin solder.

Ortho-phosphoric acid (undiluted) always worked well for me when making low temperature research kit with very thin-wall ss tubes - usually soldered to ss, brass or copper.

I think I found it in this book - I used to refer to it a lot, but I seem to have mislaid the book now so I can't check.

WJ Tegart, "The Electrolytic and Chemical Polishing of Metals in Research and Industry" (Pergamon Press, Inc., London, 1959)

Mike

Is that the Dunton's stainless flux? I use that myself, but I think it is mostly muriatic acid.

The Dunton's works for lead-tin, silver-tin as well.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

"Stay-Brite" and similar silver-bearing soft solders and common zinc chloride fluxes will usually work reasonably well. The silver content improves 'wetting' and adds strength. Hard soldering is often better with S.S., but soft soldering is possible.

Dan Mitchell ==========

Randy Replogle wrote:

a decade and a half ago i used to solder a lot of stainless tube for cryogenic use, for pressures ranging from vacuum thru 34 bar

silver braze is better if the specs allow

acid flux will eventually eat holes

clean with hot water very well

A
x?=»nÃ0Ew?&£ ú?G?A·.³rL[?%1?èéÐo¯?"]?Kâ\¼ù×L¼ÿ??È ï{"¾ ñIò³"¶R8?ÍÇDO?B;a19bæ0?Ýb[?¯C?Ë÷ºªa³?· TÍz1
@vÐ?ÿäoB1_vE±rÈh U?§âç*MO¾ª?¢óò[»±?®o#?~Ñ4´M¹2m`©A±=úø¿ø??tSLBó"ø¯½b:jç³ù4D¡Ð\ Ë>?ztz(%ð ?ÑnZ?Îe1F°ÈÒt2(Éäõl?L²_?NlV